Class Variable behaving like Instance Variable (Python 3.4)

Question

Python 3.4.0a1
Windows 8.1

Class Created:

class Bank(object):  
    bankrupt = False  

Command entered in IDLE __main__

Answer 1

After assignment to instance variable it is created if it was not before. And next time You try to access it You got it from instance __dict__.

>>> class A:
...     foo = 'b'
...     bar = []
... 
>>> a = A()
>>> b = A()
>>> a.__dict__
{}
>>> a.foo = 'c'
>>> a.foo
'c'
>>> a.__dict__
{'foo': 'c'}

This is why You have different values for a.foo and b.foo Meanwhile If You modify variable (not reassign it) You will got result which You have described.

>>> a.bar.append(1)
>>> b.bar
[1]
>>> a.bar
[1]
>>> a.__dict__
{'foo': 'c'}

In this case instance variable was not created.